How do economies enter new economic activities? In this talk, I will summarize recent advances in the study of economic diversification, knowledge diffusion, and collectivelearning. I will start by presenting the three basic principles of collectivelearning: the principle of improvement, the principle of relatedness, and the principle of knowledge intensity. Then, I will move to more recent findings showing how to define optimal strategies within the constraints defined by these principles, how to unpack the idea of relatedness of activities by using data on the work history of all of the individuals in a large country, and what are the consequences of these principles for the spatial distribution of economic activity. Finally, I will present work on the creation and construction of large scale data visualization tools (datausa.iodatachile.iodataafrica.ioatlas.media.mit.edu) and show how these are changing the way in which governments and companies organize and deliver their data.